Profits at BT dipped in the second quarter partly due to higher payments for sports rights and a slowdown in its global corporate services division.
The company said other factors holding back profits included investment in customer service, and higher pension costs and business rates.
Pre-tax profits for the three months to 30 September fell 1% to £666m
BT said it was taking "robust actions" to improve the performance of global services.
The company said market conditions in the division continued to be "challenging". It is cutting back staff numbers and has shed 1,500 posts so far this year, with a further 1,500 roles to go in the second half of the year. Another 1,000 will be cut next year.
BT said operating costs in its consumer business had risen by 2%, due to investment in new UK customer service roles and additional sports rights costs from the Premier League, Box Nation and the Ashes.
Investment in customer services has led to an improvement in waiting times, with calls now answered almost four minutes faster than last year, on average after 74 seconds.
BT chief executive Gavin Patterson said the company's cost-cutting programme was on track to deliver savings of £400m.
He also said BT was "committed" to delivering ultrafast internet speeds to 12 million premises by the end of 2020.
BT, which bought mobile operator EE last year, said it added 279,000 mobile subscribers in the past quarter taking the total number of its contract customers to 17.3 million. In total, it now has almost 30 million mobile customers.
The company also said it was continuing to sort out its Italian business, where earlier this year it said it had uncovered years of "inappropriate behaviour" and improper accounting practices.